Hybrid Light-Ultrasound Imager for Enhanced Ocular Lesion Assessment

Abstract

Purpose : This research explores the feasibility of a novel hybrid imaging system by integrating a fundus camera with a transparent ultrasound transducer, offering dual functionality: capturing widefield fundus images and guiding the ultrasound probe for detailed 3D analysis of ocular lesions.

Methods : The hybrid light-ultrasound system design was tested using a 40 MHz transparent transducer (Fig. 1a) integrated with a handheld portable fundus camera (Fig. 1c) on an eleven-month-old male Sprague Dawley rat. An optical fiber delivered 530nm illumination light through the rat's eyelid, allowing for simultaneous fundus imaging and ultrasound A-scan (Fig. 1b). The study further explored the effect of ultrasound probe transparency on image quality in human eyes by initially utilizing an eye model with the system, subsequently substituting the ultrasound transducer with a glass window of similar thickness.

Results : Figure 2a shows results from the rat eye experiment, with Fig. 2a1 showing the fundus image and Fig. 2a2 showing the ultrasound pulse-echo image. The fundus image reveals the retinal vascular structures and optic nerve, while the ultrasound delineates four anatomical landmarks: the cornea, anterior and posterior lens capsules, and the retina (peaks P1-P4 in Fig. 2a2). Figure 2b compares the imaging capabilities of a transparent transducer and an optically neutral glass window in an eye model. The transparent transducer image shows retinal vessels but with less clarity for smaller vessels than the glass window, suggesting a minor image quality reduction. Despite its limitations, the transparent transducer facilitates the integration with a fundus camera to precisely direct the ultrasound measurement.

Conclusions : The hybrid light-ultrasound imaging system presents a promising approach for precise intraocular lesion assessment, suggesting significant potential for future clinical applications in ocular diagnosis.

This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.

 

Figure 1(a1) Schematic illustration of the transparent transducer. (a2) Photographic illustration of the transparent transducer. (b) Schematic illustration of experimental setup. (c) Photographic illustration of the hybrid light-ultrasound imager. G: Ground, W: Wire, RCP: Retina conjugate plane.

 

Figure 2(a1) In vivo fundus image of a rat eye. (a2) Corresponding ultrasound pulse-echo image. (b1) Fundus image from an eye model. (b2) Fundus image of the model eye after replacing the ultrasound transducer with a glass window.